Cellular Network

We develop an unsupervised approach to condition monitoring of cellular networks using competitive neural algorithms. Training is carried out with state vectors representing the normal functioning of a simulated CDMA2000 network. Once training is completed, global and local normality profiles (NPs) are built from the distribution of quantization errors of the training state vectors and their components, respectively. The global NP is used to evaluate the overall condition of the cellular system. If abnormal behavior is detected, local NPs are used in a component-wise fashion to find abnormal state variables. Anomaly detection tests are performed via percentile-based confidence intervals computed over the global and local NPs. We compared the performance of four competitive algorithms (WTA, FSCL, SOM and Neural-Gas) and the results suggest that the joint use of global and local NPs is more efficient and more robust than current single-threshold methods. and Wideband CDMA, respectively, which are 3G technologies capable of providing speeds of up to 2Mbits/sec. 2 CDMA2000, also called 1xRTT (single carrier radio transmission technology), is a 3G wireless technology based on the CDMA platform which has the capability of providing speeds of up to 144 Kbps.

Present a collection of slides covering the following topics: ATM communications; integrated communication-navigation and surveillance; next generation concept; air-to-ground communication; air-to-air communication; cellular network; aeronautical communications; and free space optical technology.

This paper actualizes the classification of location management methods published up to now and presents results of a related extensive performance comparison of the most important paradigms for location management in cellular networks. First, a universal structure of a performance analysis framework for location management methods is defined and analyzed. Then, both a user mobility model and a specific simulation environment claiming to be as realistic as possible are suggested and implemented. Finally, the simulation framework obtained is used for a systematic comparative performance analysis of a representative sample of the most important location management schemes. The overall conclusion is that a location-area based location management method designed around a profile or history-based direction information offers the absolute best performance, in terms of location management cost, compared to all other alternative approaches. The key difference from previous works in literature is clearly underlined concerning both mobility modeling and novel location management schemes.

Internet connectivity is nowadays an ubiquitous service. However, on the road we obtain access using costly and limited data cellular network subscriptions. This, along with significant network congestion, severely limits network use. Opportunistic access to indoor APs is limited by three factors. First, establishing a link to an AP requires a significant amount of time, and, second, links on the street usually have poor quality. Third, the lifetime of this link is very short in a moving car, due to indoor APs generally covering small areas of the street. Combined, these factors thwart opportunistic use of APs for Internet access. In this paper, we propose a novel approach that leverages the large number of parked cars to separate these three factors and tackle them independently: a parked car can connect to an AP with a link that, despite its poor quality, has a long lifetime. A moving vehicle can instead benefit from the better link with a parked car and use it as a relay. As our experiments show, our approach enables the use of this free, high throughput channel for a number of non time-sensitive applications, thus reducing cost and the load on the cellular network.

In this paper faults are processed and models of faults in telecommunications networks are proposed in relation to services and revenues. The probability of faults occurring is estimated. Cost models are presented predicting the amount of revenue loss. We relate faults to services with detailed relationship between them being shown.

We consider a network that comprises a group of K users, equipped with single-antenna terminals, who want to selfishly maximize their individual transmission rates and S single-antenna base stations. The information rates and the transmit power levels of the users are not dictated by the base stations. In this context we introduce the problem of decentralized handovers: each terminal is equipped with a cognitive radio used to sense the quality of its links with the different base stations and share, in a smart way, its transmit power among them. In the hard handover case, for which there is a unique stable Nash equilibrium, we determine the selfish repartition of the users between the base stations and then we assess its social efficiency, which is measured in terms of sum-rate. In the soft handover case, the problem consists in determining the optimum selfish power allocation for each user and analyzing its sum-rate efficiency with respect to the equivalent virtual K × S multiple input multiple output (MIMO) network. We also show how to extend the provided results to the case of multi-antenna terminals and base stations and provide simulations to illustrate the presented results.

The growing need of the driving public for accurate traffic information has spurred the deployment of large scale dedicated monitoring infrastructure systems, which mainly consist in the use of inductive loop detectors and video cameras. On-board electronic devices have been proposed as an alternative traffic sensing infrastructure, as they usually provide a cost-effective way to collect traffic data, leveraging existing communication infrastructure such as the cellular phone network. A traffic monitoring system based on GPS-enabled smartphones exploits the extensive coverage provided by the cellular network, the high accuracy in position and velocity measurements provided by GPS devices, and the existing infrastructure of the communication network. This article presents a field experiment nicknamed Mobile Century, which was conceived as a proof of concept of such a system. Mobile Century included 100 vehicles carrying a GPS-enabled Nokia N95 phone driving loops on a 10-mile stretch of I-880 near Union City, California, for 8 hours. Data were collected using virtual trip lines, which are geographical markers stored in the handset that probabilistically trigger position and speed updates when the handset crosses them. The proposed prototype system provided sufficient data for traffic monitoring purposes while managing the privacy of participants. The data obtained in the experiment were processed in real-time and successfully broadcast on the internet, demonstrating the feasibility of the proposed system for real-time traffic monitoring. Results suggest that a 2-3% penetration of cell phones in the driver population is enough to provide accurate measurements of the velocity of the traffic flow.

In this paper, we investigate the impact of retrial phenomenon on loss probabilities and compare loss probabilities of several channel allocation schemes giving higher priority to hand-off calls in the cellular mobile wireless network. In general, two channel allocation schemes giving higher priority to hand-off calls are known; one is the scheme with the guard channels for hand-off calls and the other is the scheme with the priority queue for hand-off calls. For mathematical unified model for both schemes, we consider theMAP 1,MAP 2/M/c/b, ∞ retrial queue with infinite retrial group, geometric loss, guard channels and finite priority queue for hand-off class. We approximate the joint distribution of two queue lengths by Neuts' method and also obtain waiting time distribution for hand-off calls. From these results, we obtain the loss probabilities, the mean waiting time and the mean queue lengths. We give numerical examples to show the impact of the repeated attempt and to compare loss probabilities of channel allocation schemes.

The millimeter wave (mmWave) frequency band is seen as a key enabler of multi-gigabit wireless access in future cellular networks. In order to overcome the propagation challenges, mmWave systems use a large number of antenna elements both at the base station and at the user equipment, which lead to high directivity gains, fully-directional communications, and possible noise-limited operations. The fundamental differences between mmWave networks and traditional ones challenge the classical design constraints, objectives, and available degrees of freedom. This paper addresses the implications that highly directional communication has on the design of an efficient medium access control (MAC) layer. The paper discusses key MAC layer issues, such as synchronization, random access, handover, channelization, interference management, scheduling, and association. The paper provides an integrated view on MAC layer issues for cellular networks, identifies new challenges and tradeoffs, and provides novel insights and solution approaches.

This paper provides an overview of cellular networks and wireless Internet. It focuses on the problems of providing multimedia services over these networks, and highlights the latest developments in the area. This is done by providing brief descriptions, and providing a wealth of pointers to where the relevant information can be obtained. The paper consists of four main sections corresponding to protocol layering: wireless data link layer for cellular systems and the supporting of multimedia in these environments; wireless network layer, namely Mobile IP needed to support mobility in a wireless Internet; wireless transport layer, namely the extensions to Internet's TCP; wireless application layer. Regarding cellular systems, we present an overview of multiple access techniques, transmission aspects, and quality of service issues in the data link layer of these systems. The section on wireless network layer provides a brief introduction to the Internet technologies, then it illustrates the deficiencies of the current Internet Protocol (IP) for supporting wireless/mobile applications and shows how the new Mobile IP protocol overcomes these deficiencies, and how mobility is handled in these wireless Internets. The next section tackles the problem of reliable communication in wireless Internet, and the related problems of TCP over Mobile IP. The final section focuses on application layer issues in wireless data, namely handover and developing Web applications for mobile computers.

In an integrated cellular/satellite system for mobile communications a satellite subsystem cooperates with a terrestrial cellular network for providing user services. The paper addresses the problems related of the reuse of the procedures of the GSM cellular standard in an integrated system, allowing at most changes only at the mobile terminal and/or in the satellite network. The results of the study show that most of the GSM procedures can be reused in an integrated system (in a few cases with limited protocol variations) but some others would require modifications to the cellular network. The results of this study shall also be useful for the suitable definition of the protocols of an integrated satelliteherrestrial system for the next generation of mobile and personal communication services.

The need for increased individual mobility has resulted in a significant and continuous increase of road traffic density. More and more, the roads are getting congested. Modern Intelligent Transportation Systems (ITS) are offering methods to avoid these congestions. However, this requires a dense surveillance system of sensors that is very costly. Thus, due to financial constraints, not all roads are

In this paper, we present a multiagent algorithm for the frequency assignment problem in cellular radio networks. The algorithm, that has been successfully applied to GSM networks, efficiently assigns frequencies to each radio cell satisfying the constraints given by a compatibility matrix.

The tremendous advances in wireless networks, mobile computing, and sensor networks, along with the rapid growth of small, portable and powerful computing devices, offers more and more opportunities for pervasive computing and communications. This topic deals with cutting-edge research in various aspects related to the theory and practice of mobile computing or wireless and mobile networking. These aspects include architectures, algorithms, networks, protocols, modeling and performance issues, data management, ...

In this paper a wavelet-based steganographic method is proposed for robust short-message hiding. The message is embedded into the most significant wavelet coefficients of a cover image to provide invisibility and resistance against lossy transmission over cellular networks, compression or other distortion. The architecture consists of three modules. In the first module the initial message is enciphered by an encryption

In this paper, we focus on broadband wireless mesh networks like 3GPP LTE-Advanced. This technology is a key enabler for next generation cellular networks which are about to increase by an order of magnitude the capacity provided to users. Such an objective needs a significative densification of cells which requires an efficient backhauling infrastructure. In many urban areas as well as under-developed countries, wireless mesh networking is the only available solution. Besides, economical and environmental concerns require that the energy expenditure of such infrastructure is optimized.

This work addresses analytically the impact of multi-cell, multi-operator interference on the overall radio resources when multiple operators co-exist and share a common pool of spectrum. We propose a centralised dynamic spectrum allocation (DSA) scheme that is able to measure the interference level and interact dynamically to minimise interference and enhance spectrum utilisation while maintaining a satisfactory level of QoS. Furthermore, a concise system model and framework able to describe the interaction among different operators is presented.

We demonstrate a 60 GHz broadband picocellular Radio-over-Fiber network architecture that enables seamless connectivity for highly mobile end-users. Its seamless communication capabilities arise by the supported handover scheme that relies on a novel Moving Extended Cell (MEC) concept. MEC exploits user-centric virtual groups of adjacent cells that transmit the same data content to the user and utilizes a switch mechanism for restructuring the virtual multi-cell area according to the user's mobility pattern, so that a virtual antenna group moves together with the mobile user. We present the theoretical formulation for MEC and show that it can provide zero packet loss and call dropping probability values in high-rate wireless services for a broad range of mobile speeds up to 40 m/sec, independently of the fiber link distances. We also demonstrate the physical layer network architecture and switch mechanism both for a RoF network with a single 60 GHz radio frequency (RF) over each wavelength, as well as for a RoF configuration supporting simultaneous multi-RF channel transmission over each optical wavelength. The performance of the multi-RF-over-network implementation is evaluated via simulations showing successful 100 Mb/s radio signal transmission over fiber links longer than 30 km. To this end, MEC can enable seamless connectivity and bandwidth guarantees in 60 GHz picocellular RoF networks being also capable of serving multiple users over the same wavelength in a RF frequency-division-multiplexed (FDM) approach.

Optical fiber offers many advantages over coaxial cable for the transmission of radio frequency ͑rf͒ signals in antenna-remoting applications, as well as cellular networks and cable television ͑CATV͒ signal distribution networks. Optical fiber shows significantly less loss, can support signals demanding much higher bandwidth, is immune to electromagnetic interference ͑EMI͒, and enables considerable size and weight savings when compared to coaxial cable. Free-space optics ͑FSO͒ communications is a technology that uses modulated optical beams to transmit information line of sight through the atmosphere. FSO can be deployed faster and cheaper when compared with optical fiber. Recently, FSO has been investigated by the telecommunications industry and research centers to transport digital signals for civilian "last mile" applications and military applications. We demonstrate the successful transport of modulated rf analog signals over an FSO link and compare key performance measures against a fiber optic link configured in an identical manner. Results of measurements of optical power, transmission response, reflection response, group delay that defines phase distortion, carrier-to-noise ratio ͑CNR͒, and dynamic range that defines nonlinear distortion are presented. Results from this comparative study indicate that FSO for rf applications is a suitable replacement for fiber optic transmission links over short distances.

The spallation failure of a commercial thermal barrier coating (TBC), consisting of a single-crystal RENE N5 superalloy, a platinum aluminide (Pt-Al) bond coat, and an electron beam-deposited 7 wt pct yttria-stabilized zirconia ceramic layer (7YSZ), was studied following cyclic furnace testing. In the uncycled state and prior to deposition of the ceramic, the Pt-Al bond-coat surface contains a cellular network of ridges corresponding to the underlying bond-coat grain-boundary structure. With thermal cycling, the ridges and associated grain boundaries are the sites of preferential oxidation and cracking, which results in the formation of cavities that are partially filled with oxide. Using a fluorescent penetrant dye in conjunction with a direct-pull test, it is shown that, when specimens are cycled to about 80 pct of life, these grain-boundary regions show extensive debonding. The roles of oxidation and cyclic stress in localized grain boundary region spallation are discussed. The additional factors leading to large-scale TBC spallation are described.

The analysis and simulation of electromagnetic (EM) wave propagation represent a crucial task in planning cellular networks for mobile communication. When an adequate building database is available, deterministic 3D ray tracing techniques are quite useful and accurate to face this problem, but since their computational complexity is time consuming, a preprocessing step is necessary. Such a step allows the practical use of 3D ray tracing simulations so as to achieve the same accuracy of the ray optical approach in short simulation time. The preprocessing phase is independent on the position of the transmitter’s antenna, consequently it can be run once and for all, independently on EM field strength simulations. This strategy makes the technique practical and useful in common cellular network design, such as UMTS cellular planning. During the preprocessing phase, the mutual visibility between the walls and edges of the buildings are pre-evaluated and stored: the mutual visibility is d...

Anomaly detection is a pattern recognition task whose goal is to report the occurrence of abnormal or unknown behavior in a given system being monitored. In this paper we propose a general procedure for the computation of decision thresholds for anomaly detection in mobile communication networks. The proposed method is based on Kohonen's Self-Organizing Map (SOM) and the computation of nonparametric (i.e. percentile-based) confidence intervals. Through simulations we compare the performance of the proposed and standard SOM-based anomaly detection methods with respect to the false positive rates produced.

Complex cellular networks regulate metabolism, environmental adaptation, and phenotypic changes in biological systems. Among the elements forming regulatory networks in bacteria are regulatory proteins such as transcription factors, which respond to exogenous and endogenous conditions. To perceive their surroundings, bacteria have evolved sensory regulatory systems of two-components. The archetype of these systems is made up of two proteins-a signal sensor and a response regulator-whose genes are usually located together in a single transcription unit. These units switch transcriptional programs in response to environmental conditions. Here, we study 14 two-component systems in Escherichia coli, which have been experimentally characterized with respect to their transcriptional regulation and their perceived signal. Given that the activity of these sensory units is connected to the rest of the transcriptional network, we first classify them as autonomous, semiautonomous or dependent, according to whether or not they use additional regulators to be transcribed. Next, we use discrete-time models to simulate their qualitative regulatory dynamics in response to their transcriptional regulation and to the activation of these systems by their cognate signals. Compared to more traditional ordinary differential equations method, ours has the advantage of being computationally simple and mathematically tractable, while keeping the ability to reproduce the phenomenology described by non-linear models. The aim of the present work is not the study of all possible behaviors of these two-component systems, but to exemplify those behaviors reported in the literature. On the other hand, most of these systems are auto-activating switches, a property that distinguishes them from the other transcription factors in the regulatory network, which are mostly auto-repressing. Based on the data, our models show dynamic behaviors that explain how most of these sensory systems convey abilities for multistationarity, and these dynamic properties could explain the phenotypic heterogeneity observed in bacterial populations. Our results are likely to have an impact in the design of synthetic signaling modules.

The current 3GPP working assumption on the Evolved Universal Terrestrial Radio Access (E-UTRA) physical layer is that it will be based on single carrier frequency division multiple access (SC-FDMA) for the uplink and orthogonal frequency division multiple access (OFDMA) for the downlink. According to the concept specification, inter-cell interference mitigation techniques applicable to SC-FDMA and OFDMA systems are expected to be the key radio resource management techniques for E-UTRA. In this paper we propose and analyze a simple reuse partitioning technique (assuming coordinated subcarrier allocation in the cells) that is able to minimize intercell interference. We propose a model that is able to take into account that sessions dynamically enter and leave the system. Rigid sessions require a class-specific fixed number of subcarriers, while elastic sessions can enter the system if a minimum number of sub-carriers is allocated to them. In this rather general setting we analyze the system performance in terms of the expected number of sub-carrier collisions, the session blocking probabilities and the signal-to-noise-and-interference ratio performance. We present numerical results on the various trade-offs between these measures that provide insight into the behavior of OFDM based cellular systems and help dimension the parameters of a reuse partitioned system.

As the complexity of commercial cellular networks grows, there is an increasing need for automated methods detecting and diagnosing cells not only in complete outage but with degraded performance as well. Root cause analysis of the detected anomalies can be tedious and currently carried out mostly manually if at all; in most practical cases, operators simply reset problematic cells. In this paper, a novel integrated detection and diagnosis framework is presented that can identify anomalies and find the most probable root cause of not only severe problems but even smaller degradations as well. Detecting an anomaly is based on monitoring radio measurements and other performance indicators and comparing them to their usual behavior captured by profiles, which are also automatically built without the need for thresholding or manual calibration. Diagnosis is based on reports of previous fault cases by identifying and learning their characteristic impact on different performance indicators. The designed framework has been evaluated with proof-of-concept simulations including artificial faults in an LTE system. Results show the feasibility of the framework for providing the correct root cause of anomalies and possibly ranking the problems by their severity.

We present a simple queueing model to analyze the SMS capacity of a GSM cellular network. The analy- sis is based on a detailed study of GSM channels and their usage by SMS and other traffic. We saw that SMS is sent on the same control channels that are used by voice call set-up and location updates. Our results show

Customer retention (CR), loyalty (CL), and satisfaction (CS) are important (intermediate) goals for telecommunication network operators on their way to superior economic success in the liberalised German market. Therefore, drawing on a sample of 684 residential customers of digital cellular network operators in Germany this study tests hypotheses suggesting that CR, CL, and CS should be treated as differential constructs which are causally inter-linked. LISREL analyses support a two-staged model in which overall CS has a significant impact on CL which in turn influences a customer's intention to terminate/extend the contractual relationship with his mobile cellular network operator (=CR). Mobile service price and personal service benefit perceptions as well as (lack of) number portability between various cellular operators were identified as supply-related variables with the strongest effects on CR. Mobile network operators’ perceived customer care performance had no significant impact on CR. The findings suggest that an important lever for regulators to promote competition in cellular markets is the enforcement of efficient number portability procedures between mobile network operators.

Support of voice services, whether via direct customer care agent, IVR, or deposit of voicemail, is done in real time. Real-time data support might be via Web access frequently asked questions, an avatar, or an online customer care agent using instant messaging. These require real-time interactive responses but low data volumes. The help desk function might also include nonreal time (IVR and data) support for both MFI personnel and MFI customers. Nonreal-time support can involve call back or use of chat, voicemail, or electronic mail to correspond with the person making the request. Basic connectivity and access to such services are all that is required.

The field of radio network planning and optimization (RNPO) is central for wireless cellular network design, deployment, and enhancement. Wireless cellular operators invest huge sums of capital on deploying, launching, and maintaining their networks in order to ensure competitive performance and high user satisfaction. This work presents a lab course composed of 10 experiments that cover the different phases of RNPO for various state-ofthe-art wireless technologies such as GSM, UMTS, and WiMAX. Each experiment constitutes a complete entity including the necessary theoretical background and references, the lab tasks based on real-world scenarios, and a research component consisting of general questions. The proposed lab course represents a novel initiative to increase interactive learning by integrating communications theory fundamental knowledge with state-of-the-art wireless communications software tools and measurement equipment. The experiments are carefully designed to enhance the analytical skills and to advance the academic and practical knowledge of the students.

The increasing computing and communication power of new terminals in mobile networks has converted these smart phones into Internet hosts. They can be used for traditional services, such as browsing or e-mailing, but also as platforms for specific new IP multimedia services like Push to Talk, streaming or IPTV. However, developing new services or porting existing popular ones should be done considering the target network in which the services will be deployed.

This paper reviews the methods and technologies for congestion pricing of roads. Congestion tolls can be implemented at scales ranging from individual lanes on single links to national road networks. Tolls can be differentiated by time of day, road type and vehicle characteristics, and even set in real time according to current traffic conditions. Conventional toll booths have largely given way to electronic toll collection technologies. The main technology categories are roadside-only systems employing digital photography, tag and beacon systems that use short-range microwave technology, and in vehicle-only systems based on either satellite or cellular network communications. The best technology choice depends on the application. The rate at which congestion pricing is implemented, and its ultimate scope, will depend on what technology is used and on what other functions and services it can perform. Since congestion pricing calls for the greatest overall degree of toll differentiation, congestion pricing is likely to drive the technology choice.

The continuation of an active call is one of the most important quality measurements in cellular systems. Handoff process enables a cellular system to provide such a facility by transferring an active call from one cell to another. Different approaches are proposed and applied in order to achieve better handoff service. The principal parameters used to evaluate handoff techniques are: Forced termination probability and call blocking probability. Mechanisms such as guard channels and queuing handoff calls decrease the forced termination probability while increasing the call blocking probability. In this paper we present an overview about the issues related to handoff initiation and decision and discuss about different types of handoff techniques available in the literature.

The mechanisms underlying the production of thoughts by exceedingly complex cellular networks that construct the human brain constitute the most challenging problem of natural sciences. Our understanding of the brain function is very much shaped by the neuronal doctrine that assumes that neuronal networks represent the only substrate for cognition. These neuronal networks however are embedded into much larger and probably more complex network formed by neuroglia. The latter, although being electrically silent, employ many different mechanisms for intercellular signalling. It appears that astrocytes can control synaptic networks and in such a capacity they may represent an integral component of the computational power of the brain rather than being just brain "connective tissue". The fundamental question of whether neuroglia is involved in cognition and information processing remains, however, open. Indeed, a remarkable increase in the number of glial cells that distinguishes the human brain can be simply a result of exceedingly high specialisation of the neuronal networks, which delegated all matters of survival and maintenance to the neuroglia. At the same time potential power of analogue processing offered by internally connected glial networks may represent the alternative mechanism involved in cognition.

Over the last two decades free-space optical communication (FSO) has become more and more interesting as an adjunct or alternative to radio frequency communication. Free-space optical (FSO) communication links are most susceptible to a tremendous amount of variability and offer a real challenge for efficient, robust system design.one method of transmitting information from one place to another by sending pulses of light through an optical fiber is Fiber-optic communication , FSO communication systems will provide a large dynamic range of performance through most cases .It is a line-of-sight (LOS) technology that transmits a modulated beam of visible or infrared light through the atmosphere for broadband communications. In a way similar to fiber optical communications, free space optics uses a light emitting diode (LED) or laser (light amplification by stimulated emission of radiation) as a point source for data transmission. However, in free space optics, an energy beam is collimate...

This paper discusses essential implementation aspects of simple amplify-and-forward type repeaters from the radio network planning point of view. Different RF-repeater configurations are assessed through numerical analysis and field measurements in WCDMA network. The target of this paper is to show the important factors regarding the repeater deployment, which have significant impact on the overall cellular network efficiency. The paper shows the impact of repeater donor antenna beam width on the repeater deployment flexibility. Moreover, the impact of repeater on the optimum BS antenna tilt angle is presented using two macrocellular topologies. Finally, the significance of repeater placement in the repeater antenna line is emphasized through field measurements using an outdoor-toindoor repeater configuration for WCDMA.

This paper investigates the impacts of deploying Mobile Femtocell (MFemtocell) in LET networks. We investigate access delay, capacity, and feedback signalling overhead required for implementation of opportunistic scheduling in LTE cellular networks. We particularly study the impacts of deploying MFemtocells stations on the signalling overhead for opportunistic scheduling. Our system level simulation results indicate that one potential advantage of deploying MFemtocells can contribute to improve spectral efficiency by reducing the amount of feedback signalling.

IEEE 802.16m amends the IEEE 802.16 Wireless MAN-OFDMA specification to provide an advanced air interface for operation in licenced bands. It will meet the cellular layer requirements of IMT-Advanced next generation mobile networks. It will be designed to provide significantly improved performance compared to other high rate broadband cellular network systems. For the next generation mobile networks, it is important to consider increasing peak, sustained data reates, corresponding spectral efficiencies, system capacity and cell coverage as well as decreasing latency and providing QoS while carefully considering overall system complexity. In this paper we provide an overview of the stateof-the-art mobile WiMAX technology and its development. We focus our discussion on Physical Layer, MAC Layer, Schedular,QoS provisioning and mobile WiMAX specification.

Universal Mobile Telecommunications System (UMTS) is a third-generation cellular network that enables high-speed wireless Internet access. It can provide maximum data-rates ranging from 64kb/s to 2Mb/s in different environmental types. UMTS is designed to provide access to the existing Internet services as well as to UMTS specific services. It will augment the existing capabilities of 2G mobile networks and GPRS, and one often envisaged strategy is to offer a richer set of multimedia services. It is widely known that TCP does not perform efficiently in wireless links where the bit error rate is high enough. This paper has as main target to evaluate the performance of TCP data transfer over the UMTS air interface, by means of a rather detailed simulation model. We examine the performance of TCP over UMTS Dedicated Channels (DCHs) with different bit rates and Transmission Time Intervals (TTIs) and we represent some simulation experiments for UMTS High Speed Downlink Packet Access (HSDPA) transmissions.

Support of voice services, whether via direct customer care agent, IVR, or deposit of voicemail, is done in real time. Real-time data support might be via Web access frequently asked questions, an avatar, or an online customer care agent using instant messaging. These require real-time interactive responses but low data volumes. The help desk function might also include nonreal time (IVR and data) support for both MFI personnel and MFI customers. Nonreal-time support can involve call back or use of chat, voicemail, or electronic mail to correspond with the person making the request. Basic connectivity and access to such services are all that is required.

We propose a new approach to fault detection and diagnosis in third-generation (3G) cellular networks using competitive neural algorithms. For density estimation purposes, a given neural model is trained with data vectors representing normal behavior of a CDMA2000 cellular system. After training, a normality profile is built from the sample distribution of the quantization errors of the training vectors. Then, we find empirical confidence intervals for testing hypotheses of normal/abnormal functioning of the cellular network. The trained network is also used to generate inference rules that identify the causes of the faults. We compare the performance of four neural algorithms and the results suggest that the proposed approaches outperform current methods.

Due to the rapid expansion of road and highway system around the world, there is a growing demand to monitor vehicle traffic patterns and road status by jurisdictional agencies charged with maintaining roads and ensuring the safety and usability of various highways within their jurisdictions. The feasibility of performing effective monitoring relies on cost, complexity and scalability of the traffic monitoring system. These factors are largely determined by the communication method between the monitoring system devices. This paper presents a novel application that uses commercially available wireless protocols coupled with Internet Protocol (IP) to integrate traffic counters placed at different locations with the State of Oklahoma. The system uses commercial cellular networks as its transport medium for communication with the traffic control. The system has been tested and deployed since July 2007 by Oklahoma Department of Transportation (ODOT).

The MAC (Medium Access Control) protocols can be roughly categorized into three broad classes [16]. The xed assignment set will have schemes like TDMA, CDMA and FDMA. These proto-cols lack the exibility in allocating resources and thus have problems with con guration changes. This makes them unsuitable for dynamic and bursty wireless packet data networks. The random assignment class consisting